A CT calcium score scan can reveal calcium deposits in the walls of your heart’s arteries, but it cannot show the whole picture of your heart health. Knowing what the result means, and what it leaves out, can help you have a more useful conversation with your doctor.
If your doctor has referred you for a CT calcium score scan, you may be wondering what the scan measures and whether a low score means you can stop worrying. The result is one piece of information. It needs to be interpreted alongside your health history, risk factors and other test results.
What a CT calcium score scan measures
The scan uses computed tomography (CT) to look for calcium in the coronary arteries. These arteries carry blood to the heart muscle. Calcium can build up in the artery walls as part of a process called atherosclerosis, where fatty and other deposits accumulate over time.
A CT calcium score scan is often called a coronary artery calcium (CAC) scan. It produces images that are used to calculate a score based on the amount and distribution of calcium detected. The scan is designed to assess calcified plaque, not every type of plaque or every cause of heart symptoms.
The scan is usually performed without an injection of contrast dye. You lie on the scanner table while images are taken of your heart. You may be asked to hold your breath briefly so your chest stays still. The imaging team will explain what to expect and provide instructions for your appointment.
Your referral and any preparation instructions matter. Follow the advice given by your doctor and the imaging provider, and ask if you are unsure whether to take your usual medicines or if anything about your health could affect the scan.
What the score can tell you
The score indicates whether calcified plaque was seen and, if so, how much was detected. Your report may include an Agatston score, a commonly used method for measuring the amount and density of calcium. Your doctor may also consider how your score compares with people of a similar age and sex.
A score of zero means the scan did not detect calcified plaque in the coronary arteries. It can be reassuring in some situations, but it does not rule out all coronary artery disease. Plaque that has not calcified may not be detected, and the result cannot explain every possible cause of chest discomfort or other symptoms.
A score above zero shows that some calcified plaque was detected. Higher scores generally reflect a greater amount of calcified plaque, but the number does not provide a direct measure of how narrow an artery is. It also cannot predict with certainty whether or when someone will have a heart attack.
The result can help your doctor assess your cardiovascular risk and consider whether changes to your care are appropriate. The significance of a particular score depends on your overall circumstances, including age, blood pressure, cholesterol, diabetes, smoking history and family history.
What the scan cannot show
A calcium score scan is not the same as a test that maps the inside of the arteries or measures blood flow through them. It does not show every soft, non-calcified plaque, and it does not reliably identify whether a particular artery is significantly narrowed.
The scan is also not a general check for all heart conditions. It does not assess heart rhythm, heart valve function or the heart’s pumping ability. Other tests may be considered if your symptoms or medical history call for a different kind of assessment.
A low or zero result should not be used on its own to dismiss new or ongoing symptoms. If you have chest pain, breathlessness or other symptoms that concern you, contact your doctor promptly. Seek urgent medical help for severe or sudden symptoms, rather than waiting for a scan or report.
Similarly, a higher score does not mean that a heart attack is certain. It is a risk marker that your doctor can interpret and discuss with you. Your doctor may recommend further assessment, changes to risk factors, treatment or follow-up, depending on the full clinical picture.
How your doctor uses the result
Your doctor may recommend a calcium score scan when they are assessing cardiovascular risk and want additional information to support a decision. It is not suitable or necessary for everyone. Your doctor can explain why it has been requested in your circumstances and how the result may affect your care.
Risk assessment often brings together several details rather than relying on one test. These may include your cholesterol results, blood pressure, blood glucose, smoking status, medicines, family history and any past cardiovascular conditions. A calcium score adds information about calcified plaque, but it does not replace these other measures.
Before your appointment, consider asking what question the scan is intended to help answer. You could also ask what different score ranges might mean for your care, whether another test may be relevant, and when and how the result will be discussed with you.
After the scan, direct questions about your score and next steps to the doctor who referred you. The report is one part of the assessment, and your doctor can explain its meaning in the context of your health and decide whether any follow-up is needed.
What to expect at your appointment
A CT calcium score scan is a brief imaging examination. You will usually be asked to lie on your back and remain still. Small monitoring pads may be placed on your chest so the scanner can time images with your heartbeat. You may need to hold your breath for short periods.
The imaging staff will guide you through the process and let you know what to do. Tell them if you are pregnant or think you could be, and mention relevant health concerns or difficulties lying flat or holding your breath. Your referral information helps the team carry out the requested examination.
The scan uses X-rays, so it involves a dose of ionising radiation. Your doctor considers the reason for the referral, and the imaging team follows appropriate procedures for the examination. Ask your doctor or the imaging provider if you have questions about radiation or whether the scan is suitable for you.
After the images are taken, a radiologist reviews them and prepares a report for the referring doctor. The imaging provider does not replace the doctor’s role in explaining what the result means for your health. Ask the referring practice how and when you should expect to discuss the report.
The Takeaway
A CT calcium score scan measures calcified plaque in the coronary arteries. It can add useful information to a heart-risk assessment, but it cannot rule out all coronary disease, explain every symptom or predict an individual outcome. Your doctor interprets the result alongside your health history and other risk factors.
Ready to take the next step? Have a referral from your doctor? Contact Border Radiology Specialists to arrange your scan at a time that suits you.
Frequently Asked Questions
Does a CT calcium score scan require an injection?
The scan is generally performed without contrast dye. Follow the appointment instructions provided for your scan, and contact the imaging provider if you have questions about preparation.
How long does the scan take?
The imaging itself is usually brief, although your appointment may take longer to allow for check-in and preparation. The team can advise you about the expected appointment time.
Does a score of zero mean my arteries are completely clear?
A zero score means the scan did not detect calcified plaque. It may not detect non-calcified plaque, and it does not rule out every form of coronary disease. Your doctor should interpret the result in context.
Does a high score mean I will have a heart attack?
A higher score reflects more calcified plaque, but it cannot predict with certainty whether or when a heart attack will occur. Discuss the result and any recommended next steps with your doctor.
Can the scan explain chest pain?
The scan is not designed to diagnose every cause of chest pain or assess all forms of heart disease. Tell your doctor about your symptoms. Seek urgent care for severe or sudden symptoms.
Who explains the result?
A radiologist reviews the images and sends a report to the referring doctor. Your doctor can explain the findings alongside your medical history and discuss whether further assessment or care is appropriate.
This article provides general information only and is not a substitute for medical advice, diagnosis or treatment. Follow your doctor’s advice and discuss questions about your health or scan with a qualified health professional. Border Radiology Specialists provides medical imaging following a doctor’s referral.